package com.lemon.cloud.gateway.filter;

import cn.hutool.core.lang.UUID;
import cn.hutool.extra.spring.SpringUtil;
import com.lemon.cloud.comm.constants.CommonConstants;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.MDC;
import org.springframework.cloud.commons.util.InetUtils;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.util.List;

/**
 * 全局拦截器，作用所有的微服务
 * <p>
 * 1. 对请求的API调用过滤，记录接口的请求时间，方便日志审计、告警、分析等运维操作 2. 后期可以扩展对接其他日志系统
 * <p>
 */
@Slf4j
@Component
public class ApiLoggingFilter implements GlobalFilter, Ordered {

    private static final String START_TIME = "startTime";

    private static final String X_REAL_IP = "X-Real-IP";// nginx需要配置


    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        if (log.isDebugEnabled()) {
            String info = String.format("Method:{%s} Host:{%s} Path:{%s} Query:{%s}",
                    exchange.getRequest().getMethod().name(), exchange.getRequest().getURI().getHost(),
                    exchange.getRequest().getURI().getPath(), exchange.getRequest().getQueryParams());
            log.debug(info);
        }
        exchange.getAttributes().put(START_TIME, System.currentTimeMillis());
        ServerHttpRequest request = exchange.getRequest();
        List<String> strings = request.getHeaders().get(CommonConstants.X_REQUEST_ID);
        String traceId;
        if (CollectionUtils.isEmpty(strings)) {
            //上游服务没有，则网关作为初始点
            traceId = UUID.randomUUID().toString();
            request = exchange.getRequest()
                    .mutate()
                    .header(CommonConstants.X_REQUEST_ID, traceId)
                    .build();
        } else {
            traceId = strings.getFirst();
        }
        MDC.put(CommonConstants.X_REQUEST_ID, traceId);
        ServerHttpResponse response = exchange.getResponse();
        //将TRACE_ID 回写至response
        response.getHeaders().add(CommonConstants.X_REQUEST_ID, traceId);
        return chain.filter(exchange).then(Mono.fromRunnable(() -> {
            Long startTime = exchange.getAttribute(START_TIME);
            if (startTime != null) {
                Long executeTime = (System.currentTimeMillis() - startTime);
                List<String> ips = exchange.getRequest().getHeaders().get(X_REAL_IP);
                String ip = ips != null ? ips.getFirst() : getIp();
                String api = exchange.getRequest().getURI().getRawPath();

                int code = 500;
                if (exchange.getResponse().getStatusCode() != null) {
                    code = exchange.getResponse().getStatusCode().value();
                }
                // 当前仅记录日志，后续可以添加日志队列，来过滤请求慢的接口
                if (log.isDebugEnabled()) {
                    log.debug("来自IP：{},requestId:{}的请求接口：{}，响应状态码：{}，请求耗时：{}ms", ip, traceId, api, code, executeTime);
                }
            }
        }));
    }

    private String getIp() {
        InetUtils inetUtils = SpringUtil.getBean(InetUtils.class);
        return inetUtils.findFirstNonLoopbackHostInfo().getIpAddress();
    }

    @Override
    public int getOrder() {
        return Ordered.LOWEST_PRECEDENCE;
    }

}
